Method of dielectrically embossing risers in a trim assembly

ABSTRACT

A method for making a decorative trim assembly with a dielectric embossing press in which one of the electrodes includes a plurality of spaced embossing blades and the other electrode has a flat face formed by a yieldable material. The method comprises the steps of preforming a sheet of thermoplastic material with a plurality of risers defined by spaced trim lines followed by placing the sheet on the electrode with the embossing blades contacting the trim lines. Afterwards, a coextensive sheet of filler material is positioned onto the sheet of thermoplastic material and the electrodes are moved toward each other so as to cause the embossing blades to compress the cover sheet and the sheet of filler material into the yieldable material. Sufficient pressure is then applied to the composite sheets to cause the sheet of filler material to be split along the embossing blades to form a plurality of separate strips. This is followed by opening the press and placing a base sheet over the strips of filler material and dielectrically bonding the sheet of thermoplastic material to the base sheet along the trim lines.

Elie States Smith atent [1 1 [451 Sept. 3, 1974 [75] Inventor: KennethA. Smith, Washington,

Mich.

[73] Assignee: General Motors Corporation,

Detroit, Mich.

[22] Filed: July 24, 1972 [21] Appl. No.: 274,821

[52] US. Cl 156/219, 156/250, 156/252, 156/261, 156/267, 156/272,156/292,

[51] Int. Cl B311 7/00 [58] Field of Search 156/209, 219, 220, 290,156/250-252, 261, 262, 272, 252, 245, 211,

[56] References Cited UNITED STATES PATENTS 2,982,456 5/1961 l-lsu et a1225/2 3,026,233 3/1962 Scholl et al. 156/272 X 3,047,451 7/1962 Beck etal 156/251 X 3,116,569 1/1964 Kramer 156/245 X 3,219,506 ll/1965 Dusinaet al... 156/290 3,320,108 5/1967 Lande 156/219 3,518,334 6/1970Carrigan et al. 264/160 X 3,623,209 ll/1971 Zuhlke et al 264/163 X3,673,300 6/1972 Muhlbach et al 264/160 Primary ExaminerCharles E. VanHorn Assistant Examiner-David A. Simmons Attorney, Agent, or Firm-E. J.Bislgu p [5 7] ABSTRACT A method for making a decorative trim assemblywith I a dielectric embossing press in which one of the electrodesincludes a plurality of spaced embossing blades and the other electrodehas a flat face formed by a yieldable material. The method comprises thesteps of preforming a sheet of thermoplastic material with a pluralityof risers defined by spaced trim lines followed by placing the sheet onthe electrode with the embossing blade s contacting the trim lines.Afterwards, a coextensive sheet of filler material is position'ed ontothe sheet of thermoplastic material and the electrodes are moved towardeach other so as to cause the embossing blades to compress the coversheet and the sheet of filler material into the yieldable material.Sufficient pressure is then applied to the composite sheets to cause thesheet of filler material to be split along the embossing blades to forma plurality of separate strips. This is followed by opening the pressand placing a base sheet over the strips of filler material anddielectrically bonding the sheet of thermoplastic material to the basesheet along the trim lines.

4 Claims, 12 Drawing Figures METHOD OF DIELECTRICALLY EOSSING RISERS INA TRIM ASSEMBLY The invention concerns a dielectric embossing method forforming a plurality of risers in a decorative trim assembly of the typethat may be used for covering the seats in an automobile. One methodpresently used for forming risers in trim assemblies consists ofpositioning a laminate of trim materials onto a plurality of parallelupstanding blades of a dielectric embossing press. The laminate usuallyconsists of a cover sheet made of thermoplastic material, a filler pad,and a base sheet. The filler pad usually takes the form of a cotton typematerial which is impregnated with a heat fusible plastic; and when theassembly is dielectrically embossed, the blades serve to bond the coversheet to the base sheet through the filler pad with the plastic in thelatter being melted and cured along the embossed lines and serving asthe bonding adhesive. As is well known, the greater the loft provided bythe risers, the more attractive the trim assembly is to the observer inthat it appears to provide a more luxurious cover. By using theaforedescribed process, however, it has been found that the thickness ofthe tiller pad and, accordingly, the height of the riser must be limitedto some extent because the embossing blades are required to compress thefiller te'df tm nethst i .l nes nd at 11 6535 6 time must provide a bondthrough the compressed material to the base sheet. It is inevitable thatduring such operation, a certain amount of the filler pad is locatedbetween the coversheet and the base sheet along the trim line so as toprevent direct bonding therebetween. As a result, a maximum height risercannot be obtaine when utilizing the aforedescribed method.

The present invention concerns a method for dielectrically embossing andforming a trim assembly with risers of increased height. In this case,the filler pad is made from a polyurethane foam type material having arelatively low tensile strength and percent elongation so as to allowthe material to separate when subjected to compression along relativelythin lines. The method according to the invention forms the filler padinto a plurality of strips which subsequently are pressed between theembossing blades followed by a lateral shifting of the base sheet in areciprocating fashion. The latter movement of the base sheet serves toassure that the strips are located between the embossing blades and alsoserves to remove any particles of the tiller pad remaining above theblades due to the compression cutting operation of the tiller pad.

The apparatus utilized for practicing the invention comprises a lowerelectrode which supports a series of substantially parallel upstandingembossing blades which serve to initially support the cover sheet andthe tiller pad. A plate member which can be attached to the upperelectrode has a flat lower face made of yieldable material which isadapted to be lowered into physical engagement with the filler pad andunder the urging of the upper electrode serves to compress the fillerpad with sufficient force so as to cause the latter to be split intoindividual strips by the embossing blades. In addition, the plate memberincorporates vacuum operated means for holding the base sheet to theflat face after which the plate member is reciprocated in a planeparallel to the flat face for clearing the area above the embossingblades as described above. The reciprocating movement of the platemember is accomplished through air-actuated actuators supported by thelower electrode on opposite sides of the plate member.

Accordingly, the objects of the present invention are to provide amethod for formingrisers in a trim assembly that utilizes a dielectricembossing press for splitting a filler pad into a plurality of strips;to provide a method for dielectrically forming a trim assembly withrisers that reciprocates a base sheet in a horizontal plane so as toassure that precut filler strips for the risers are located between theembossing blades; and to provide a method of dielectrically embossingrisers into a trim assembly wherein a base sheet is reciprocatedrelative to a cover sheet so as to clean the area located on the coversheet above the embossing blades prior to dielectrically bonding thesheets together.

Other objects and advantages of the present invention will be apparentfrom the following detailed description when taken with the drawings inwhich:

FIG. 1 is a plan view showing a dielectric embossing apparatus used forpracticing the invention;

FIG. 2 is a sectional view of the apparatus of FIG. 1 taken on line 2-2;

FIG. 3 is a sectional view of the apparatus of FIG. 1 taken on line 3-3;

FIG. 4 is a view showing a thermo-forming mold used for preforming thecover sheet of thermoplastic material used with the invention;

FIG. 5 shows the embossing blades of the apparatus of FIGS. 1 through 3supporting the preformed cover sheet and a sheet of polyurethane foam;

FIG. 6 shows the assembly of FIG. 5 being compressed between the upperelectrode and the lower electrode;

FIG. 7 shows the polyurethane foam split into a plurality of strips as aresult of the'operation shown in FIG.

FIG. 8 shows the upper electrode supporting the base sheetand engagingthe strips of FIG. 7;

FIG. 9 shows the positions of the various elements of the trim assemblyduring the reciprocating movement of the plate member which forms a partof the upper electrode;

FIG. 10 is an enlarged view showing in detail the manner that the basesheet removes particles located above the embossing blades;

FIG. 11 is similar to FIG. 10 and shows the cover sheet being directlybonded to the base sheet; and

FIG. 12 shows the finished trim assembly with the risers being trimmedby a cutting tool.

Referring to the drawings and more particularly FIGS. 1, 2 and 3thereof, a dielectric embossing press is shown comprising a lowerstationary electrode 12 and an upper movable electrode 14, both of whichare connected in series with a high frequency alternating currentgenerator 16. The upper electrode 14 is movable along a vertical axisthrough operating means (not shown) toward and away from the lowerelectrode 12, while the generator 16 is capable of impressing analternating current at a frequency between I and 100 megacycles betweenthe electrodes.

The lower electrode 12 includes a fixed base frame 18 which rigidlycarries a rectangular support 19 having a plurality of identicalupstanding parallel embossing blades 20, all of which are of uniformheight and length and serve to support a trim assembly in a manner thatwill be described hereinafter. As best seen in FIG. 2, the embossingblades 20 are equally spaced from each other so as to provide risers ofequal width in the trim assembly to be formed. It will be understoodthat the spacing between the embossing blades 20 can be varied dependingupon the particular design effect which one wishes to provide inthe'trim assembly. Adjacent each side of the support 19 is a centeringdevice 22 consisting of a pair of spring biased plungers 24 and 26respectively housed within suitably bored retainers 28 and 30 as seen inFIG. 3. Each centering device 22 is centrally located intermediate theends of each side of the support 19 and is rigidly secured to the baseframe 18. The support 19 is also surrounded by four identical actuatordevices 32, 34, 36 and 38 which together form a rectangle. Each actuatordevice includes an elongatedexpandable member 40 made of rubber or asimilar elastomeric material and,in its normal position, takes the formas shown in FIG. 2. Each of the expandablemembers 40 has a hollowinterior and extends substantially the full length of a support bracket42 rigidly secured to a stanchion 44 which in turn is'fixed with thebase frame 18. In cross section, the expandable member 40 is generallyE-shaped and comprises an outwardly projecting plunger 46 integrallyformed with a pair of diverging arms 48 and 50. The arms 48 and 50in'turn are integral with a pair of legs 52 and 54 which are fixed witha vertically extending base 56 held by the support bracket 42. Theexpandable member .40 is sealed at the opposite ends thereof so as toform a completely enclosed chamber which communicates through a port 58with a fitting 60 which in turn is connected with a flexible hose. Thus,as seen in FIG. 1, the actuator devices 32, 34, 36, and 38 connect withhoses 62, 64, 66, and 68 respectively which in turn lead to a source ofpressurized fluid indicated by the numeral 70. A suitable valve 72 islocated in each of the airlines for selectively controlling'air to theactuator device for expanding the member 40 into the phantom lineposition as shown in FIG. 2.. v

The upperelectrode 14 includes the usual support member 74 which in thiscase abuts the upper portion of a plate member 76 through a bearingassembly 78 as shown'in FIG. 2. The plate member 76 consists'of tworectangular plates80 and 82 fixed together by a plurality of cap screws,two of which are indicated by the numeral 84. Interposed between theplate member 76 and the support member 74 is the bearing assembly 78which consists of a rectangular retainer plate 86'having a plurality ofspherical balls 88 supported thereby. A pair of spring clips 90 and 92are'located on opposite sides of the retainer plate 86 to hold thelatter in position on the upper plate 80. Although not shown, the platemember 76 can be carried by the support member 74 through a means whichpermits'the plate member 76 to retain engagement with the support member74 as shown in FIG. 2 and atthe same time permits the plate member 76tobe moved laterally as a unit in a horizontal plane in a manner whichwill be hereinafter discussed.

The plate member 76 has a lower flat face 94 which is covered by a sheet93 of silicone rubber which is approximately 0.020 inch thick and thatis held to the plate 82 by four elongated relatively thin bars, each ofwhich is indicated by the numeral 96. In addition, the plate member 76is formed with a series of interconnecting passages 98, 100, 102 and 104which connect with a plurality of ports 106 which communicate withregistering openings 108 formed. in the sheet 93 of silicone rubber. Itwill be understood that a sufficient number of ports 106 andregisteringopenings 108 are provided so that a sheet of material of the type whichwill hereinafter be described can be held by the plate member 76 whenthe passages 98, 100, 102 and 104 are connected through the elbowfitting 110 and hose I 112 with a source 114 of fluid at subatmosphericpressure. A valve 116 selectively controls the supply of subatmosphericpressure to theaforementioned passages. It will also be noted that thelower plate 82 rigidly supports four downwardly depending tongues 118,120, 122 and 124, each of which is adapted to be located between theplungers 24 and 26 of one of the centering devices 22 as shown in FIG.3. Thus, with the plate member 76 located in the position of FIG. 2, thecen- 'tering devices 22 located on opposite sidesof the plate member 76serve to center the latter relative to the actuator devices 32, 34, 36and 38.

In utilizing the apparatus described above, initially thedielectric'embossing press is opened by raising the upper electrode 14so as to expose the embossing blades 20 shown in FIG. 2.'A preformedcover sheet 126 of unsupported thermoplastic material is positioned onthe upperend of the embossing blades 20 as shown in FIG. 5. In thisregard, it will be noted that the preformed sheet 126 will have aplurality of risers formed therein. The risers will be spaced vadistance which equals the spacing between the embossing blades and canbe formed with a thermo-forming mold 128 such as shown in FIG. 4 or byan embossing method such as disclosed in Ananian et al U.S. Pat. No.3,265,551; Both of these methods are well known in the art and,accordingly, it only need be mentioned that the thermo-forming methodconsists of having a preheated sheet of thermoplastic material drawnonto a suitably formed die member 130 under the influence ofsubatmospheric pressure connected with a chamber 132 which connects witha plurality of outwardly extending ports 134. The process disclosed inAnanian et al consists of compressing a cover sheet of yieldablematerial against a sheet of thermoplastic material and into-an areabetween the embossing blades and thereafter applying an alternatingcurrent of radio frequency to the portions of the cover sheetscontacting the blades so as to soften the material and remove anytension in the cover sheet. The applied pressure is then removed topermit the yieldable material to return to its normal form and leavehollow risers in the trim sheet. As should be apparent, other methodscan be utilized forpreforming the cover sheet 126 with risers so thatthe cover sheet can be placed on the embossing blades 20 as seen in FIG.5 and have the valleys located as shown. It will also be understood'thatthe cover sheet 126 should be made from a plastic such as vinylchloride, vinylidene chloride, or any other similar synthetic which canbe preformed as explained above and is compatible with a dielectricembossing process. One type of cover sheet utilized successfully forpracticing the process was a vinyl coated, crimp-knit nylon fabricmanufactured by Uniroyal, Inc., and indentified as No. S-869l, datedJune 26, 1969.

With the cover sheet 126 positioned as seen in FIG.

identified as Composition 04-24-0. Other thicknesses of the sheet 136obtained-from General Tire & Rubber Company were in the range between0.125 inch and 0.500 inch and also were used successfully for practicingthis splitting operation. Each sheet 136 of foam material consisted of aclosed cell polyurethane foam having a density of about 2 pounds percubic inch and a tensile strength between 8 and 9 psi. The foam materialalso had an elongation in the 8090 percent range. Any

other type of polyurethane foam material can be used so long as itstensile strength and percent elongation are low enough to allow the foammaterial to be split under the conditions used in the process for makingthe trim assembly as described hereinafter.

After the sheet 136 of foam material is placed onto the cover sheet 126,the dielectric embossing press is closed as seen in FIG. 6, and both thecover sheet 126 and the sheet 136 of foam material are subjected to anapplied pressure of about 700 psinThe' top surfaces of each of theembossing blades cause the cover sheet 126 to be pressed into the sheet136 of foam material which in turn tends to elongate at its uppersurface as it moves into the sheet 93 of silicone rubber carried by theplate member 76. This action causes the portions of the sheet 136located between the embossing blades 20 to be physically torn away fromeach other so as to form a plurality of elongated rectangularstrips offoam material as seen inFIG. 7. It has beenfound that the tearing orseparating action that occurs between the strips of foam material due tothe pressure applied by the embossing blades 20, results in a number offragmented particles 138 settling bet-weenadjacent strips and resting onthe cover sheet 126 immediately above the upper surface of some of theembossingblades 20 as seen in FIG. 7. Such particles 138 could preventthe cover sheet 126 from bonding completely along the embossing blades20 to the base sheet 140 seen in FIG. 8 and, for this reason, theparticles 138 should be removed from the bonding area. I

The base sheet 140 consists basically of a 5 ounce cotton osnaburg clothhaving a checkerboard surface of plasticized vinyl resin which is formedon one surface of the sheet. The checkerboard pattern can be formed byfirst placing asheet'of the aforementioned cloth on a flat table andthen placing a screen in contact with the cloth. One type of screen thatcan be used for making the checkerboard pattern consists of nylonthreads which are stretched over a rectangular wooden frame with spacingwhich allows threads per linear inch. Thereafter, a water dispersedvinyl latex such as Ge'on 576 manufactured by the B. F. Goodrich Companyis poured over the screen so that the cloth is completely wetted by thelatex. A squeegee is then used to scrape all excess latex away from thesurface of the screen leaving only that liquid which is trapped in thescreen opening. The screen is then lifted off the cloth leaving acontrolled thickness of latex film on the cloth. Thereafter, the clothis placed in an oven and dried for about 15 minutes at 200 F. It shouldbe noted that it has been found that a coating density of from 4 to 10ounces of the vinyl per square yard 'will provide an acceptable basesheet. This density can be varied by use of screens of varyingcoarseness.

The base sheet 140 made as described above is placed on the strips offoam material as seen in FIG. 7 with the checkerboard pattern of vinylfacing and engaging the strips as seen in FIG. 8. The dielectricembossingpress is then closed once again and the valve 116 is openedcausing the base sheet 140 to be held by the plate member 76 asaforedescribed. A pressure of about 5 psi is. then applied after whicheach of the valves 72 are sequentially opened and closed at a frequencyof about 60 cycles per minute. As seen in FIG. 1, assuming valve 72controlling actuator device 32 is opened and closed as indicated, theplate member 76 is caused to reciprocate in a horizontal plane along afirst axis. Afterwards, the valve 72 controlling actuator 34 can beopened and closed at the same frequency causing the plate member 76 toreciprocate again, however, this time along an axis which isperpendicular to the first axis of movement of the plate member. As theplate member 76 reciprocates as seen in FIG. 9, the base sheet 140 moveswiththe plate member 76 and the checkerboard pattern of vinyl materialextending from the base sheet 140 serves to move any particles 138located between the strips out of an area immediately above theembossing blades 20. Thus, as seen in FIG. 10, the vinyl materialprojecting from the base sheet 140 serves to contact particles 138 andmove them out of' the area which will serve as the'embossed trim linesof the trim assembly.

After the plate member 76 has been reciprocated along the mutuallyperpendicular axes, the upper electrode 14 is moved downwardly furthertoward the lower electrode 12 so as to cause the embossing blades v20 toapply a pressure between 500 and 1,000 psi to the cover sheet 126 andthe base sheet l40located above each of the embossing blades.Thereafter, an alternating current is impressed across the upper andlower electrodes, the voltage being between 1,200 and 4,000 volts and ata frequency of between 1 and l00 megacycles. The electric field isgenerated between the electrodes .for 10. seconds during which time thecover sheet 126 is fused to the base sheet 140 as seen in FIG. 1 1.

After the heat cycle is completed, the upper electrode 14 is raised andthe embossed trim assembly is removed from the press. As seen in FIG.12, the panel, formed with risers having the increased depth, is thentrimmed to the desired size by a cutting blade indicated generally bythe numeral 142. v

At this juncture, it will be noted that as seen in FIGS. 1 and 2, whenthe actuator device 36 is expanded into the phantom line position, itwill cause the plate member 76 to shift to the right until the tonguesand 124 abut the retainer housings 28 and 30 on opposite sides of theplate member 76. When the pressure is removed from the actuator deviceand the latter is simultaneously connected with air at atmosphericpressure, the spring working against the depressed plungers in thecentering devices urges the tongues 120 and 124 and accordingly theplate member 76 back to a central position. It has been found that thebest results are obtained when the actuator devices on opposite sides ofthe plate member 76 are cycled alternately. This gives the plate member76 the maximum amount of movement horizontally permitting thecheckerboard lower surface of the base sheet to act as a cleaner forremoving any particles 138 located above an embossing blade 20. It-willbe understood that the aforesaid movement of the plate member 76 occurseven though pressure is being applied by the upper electrode 14 to theplate member 76. This is possible, of course, because of the bearingassembly 78 which allows movement of the plate member 76 by having theballs 88 roll against the upper surface of the support member 74.

Various changes and modifications can be made in this constructionwithout departingfrom the spirit of the invention. Such changes andmodifications are contemplated by the inventor and he does not wish tobe limited'except by the scope of the appended claims.

I claim: I

l. A method for making a decorative trim assembly with a dielectrice'mbossing press in which one of the electrodes includes a plurality ofspaced embossing blades and the other electrode has a flat face formedby a yieldable material, comprising the steps of preforming a sheet ofthermoplastic material with a plurality of risers defined by spaced trimlines, placing said sheet of thermoplastic material on said one of theelectrodes with the embossing blades contacting the trim lines,positioning a coextensive sheet of filler material onto the sheet ofthermoplastic material, applying pressure to the compositesheets'whereby the embossing blades compressthecover sheet and the sheetof filler material into the yieldable material and cause the sheet offiller material to be split along the embossing blades to form aplurality of separate strips located between adjacent embossing blades,placing a base sheet over the strips of tiller material, moving the basesheet relative to the cover sheet to position the strips between theembossing blades and to remove particles of the filler material from thetrim line area, and dielectrically bonding the sheet of thermoplasticmaterial to the base sheet along the trim lines.

2. The method of claim 1 wherein said sheet of filler material is madeof polyurethane foam.

, 8 3; The method of claim 1 wherein the base sheet has a plurality ofoutwardly extending projections formed on one surface thereof and facingthe strips of filler ma- I terial, said projections being made from avinyl material.

4. A method for making a decorative trim assembly with a dielectricembossing press in which one of the electrodes includes a plurality ofspaced embossing blades and the other electrode has a flat face formedby a yieldable material, comprising the steps of preforming a sheet ofthermoplastic material with a plurality of risers defined by spaced trimlines, placing said sheet of thermoplastic material on said one of theelectrodes with the embossing blades contacting the trim lines,positioning a coextensive sheet of filler material onto the sheet ofthermoplastic material, moving the electrodes toward each other so as tocause the embossing blades to compress the cover sheet and the sheet offiller material into the yieldable material, applying sufficientpressure to the composite sheets to cause the sheet of filler materialto be split along the embossing blades to form a plurality of separatestrips, attaching a base sheet formed with projections to the flat faceof the other electrode so that upon closing the press the projectionscontact the strips of filler material, reciprocating the base sheet inits plane relative to the cover sheet so as to cause the projections toposition the strips between the embossing blades and to remove particlesof the filler material from the trim line area, and dielectricallybonding the sheet of thermoplastic material to the base sheet along thetrim lines.

1. A method for making a decorative trim assembly with a dielectricembossing press in which one of the electrodes includes a plurality ofspaced embossing blades and the other electrode has a flat face formedby a yieldable material, comprising the steps of preforming a sheet ofthermoplastic material with a plurality of risers defined by spaced trimlines, placing said sheet of thermoplastic material on said one of theelectrOdes with the embossing blades contacting the trim lines,positioning a coextensive sheet of filler material onto the sheet ofthermoplastic material, applying pressure to the composite sheetswhereby the embossing blades compress the cover sheet and the sheet offiller material into the yieldable material and cause the sheet offiller material to be split along the embossing blades to form aplurality of separate strips located between adjacent embossing blades,placing a base sheet over the strips of filler material, moving the basesheet relative to the cover sheet to position the strips between theembossing blades and to remove particles of the filler material from thetrim line area, and dielectrically bonding the sheet of thermoplasticmaterial to the base sheet along the trim lines.
 2. The method of claim1 wherein said sheet of filler material is made of polyurethane foam. 3.The method of claim 1 wherein the base sheet has a plurality ofoutwardly extending projections formed on one surface thereof and facingthe strips of filler material, said projections being made from a vinylmaterial.
 4. A method for making a decorative trim assembly with adielectric embossing press in which one of the electrodes includes aplurality of spaced embossing blades and the other electrode has a flatface formed by a yieldable material, comprising the steps of preforminga sheet of thermoplastic material with a plurality of risers defined byspaced trim lines, placing said sheet of thermoplastic material on saidone of the electrodes with the embossing blades contacting the trimlines, positioning a coextensive sheet of filler material onto the sheetof thermoplastic material, moving the electrodes toward each other so asto cause the embossing blades to compress the cover sheet and the sheetof filler material into the yieldable material, applying sufficientpressure to the composite sheets to cause the sheet of filler materialto be split along the embossing blades to form a plurality of separatestrips, attaching a base sheet formed with projections to the flat faceof the other electrode so that upon closing the press the projectionscontact the strips of filler material, reciprocating the base sheet inits plane relative to the cover sheet so as to cause the projections toposition the strips between the embossing blades and to remove particlesof the filler material from the trim line area, and dielectricallybonding the sheet of thermoplastic material to the base sheet along thetrim lines.